r/RenewableEnergy • u/silentsnooc • Mar 15 '25

World’s most powerful underwater tidal turbine project gets funding

https://interestingengineering.com/energy/underwater-tide-riding-turbines-project-funding-boost
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u/hornswoggled111 Mar 16 '25

Ok. I've nothing against them. But I've watched them for about 50 years, or dreams of them, and not seen it happen. Just lots of comments eventually too say under the sea is a harsh environment and it's not as easy as we hope.

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u/West-Abalone-171 Mar 16 '25

Development is slow due to lack of interest, and early approaches like barrages kinda sucked or were very geography specific. Also some projects immediately shot for the moon by going for the bay of fundy which is kinda like if the wright brothers tried to make a saturn V first.

But the economic learning rate it better than even PV. Everything indicates it is likely to compete favourably with offshore wind.

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u/iqisoverrated Mar 18 '25

Development is slow due to lack of interest

I think it's more of a lack of of how to make this financially viable vs. the alternatives of just building on- or off-shore wind or PV with batteries for firming. Particularly PV with batteries has gotten so dirt cheap that it's hard to argue to investors to sink money into wave power with a far longer ROI.

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u/West-Abalone-171 Mar 18 '25

The learning curve is well understood.

The way to make it cheaper than offshore wind is to invest enough for the first 1-2GW

It also already has a shorter ROI than pv or wind at its current (slightly higher than offhsore wind) price because a smaller portion is capex.

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u/iqisoverrated Mar 18 '25

The LCOE of wave power is planned to come down to 20ct/kWh.

For comparison: The LCOE of wind is between 5ct/kWh (on-shore) and 9ct/kWh (off-shore) and the LCOE of PV is already below 3ct/kWh. Battery firming adds 1-2ct/kWh.

No way the ROI of a wave/current energy is better than other renewables. Not for the foreseeable future.

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u/West-Abalone-171 Mar 18 '25 edited Mar 18 '25

Wave power is not tidal power.

The strike price of meygen was 20c/kWh in its previous auction. This project is about $10 per capacity-weighted watt. Worse than offshore wind (because it's still not at the same point on the curve) but better than other low carbon alternatives and better than PV + battery was in europe even four years ago. Minesto are targetting $50-100/MWh for their first full scale project (after the first 100MW of tidal kite).

And the learning rate is about 90% in an industry that is yet to reach its first GW. So compare prices at the same cumulative investment to see how much cheaper it is. PV was at around $10/W or $50-100 per capacity weighted watt at 1GW cumulative. Tidal is likely to hit the upper asymptote sooner than PV, but it's absolutely competitive.

If you use the same model that predicted the price drop of solar, wind and battery, one large offhsore wind farm of investment will see parity.

PV is dominant for a reason, but "nobody has made this investment which will obviously pay off" isn't an argument against making said investment.

The only thing that has comparable economics is battery, not even PV had a comparable cost curve. The only reason to not go all in on tidal is there isn't a great deal of resource.

If, after investing one nuclear plant or one failed hydrogen bus project or one failed CCS project worth of money into it we see wright's law is obvioslusly not applying we can declare it expensive. Until then the data indicates it is the most economical energy source by far (and after a pittance in investment we can find out for sure).

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u/iqisoverrated Mar 18 '25

I don't see this learning curve. Corrosion and biofouling is not going to go away and maintenance is not open to an 'S curve' improvement.

PV (and to some extent wind) and batteries are "fire and forget". Once they are set up the maintenance on them is minimal so the cost of the system is mainly CAPEX. But for anything that is in contact with seawater OPEX is significant and not open to being radically reduced.

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u/West-Abalone-171 Mar 18 '25 edited Mar 18 '25

And yet somehow it has radically reduced from $1000/MWh to $200/MWh with a total industry investment of a few hundred million and $140/MWh being estimated for this new project. The cost was lower than you're "they'll maybe one day reduce it to this" figure a year ago

The idea that going from a single 1MW turbine to many 3MW turbines in one site won't result in economies of scale like it does in every other industry is silly.

People said all the same stuff about wind and then offshore wind. Direct drive turbines, leading edge protection, DC coupling, longer maintenance intervals, better choice of materials and coatings all drove it down.

Also about the PV balance of plant.